The enzymatic reactions involved in the degradation of uric acid by Clostridium cylindrosporum and Clostridium acidi-urici will be investigated with particular reference to formyltetrahydrofolate synthetase and other folate enzymes. The properties of the formate activating enzyme from the clostridia will be compared with the enzyme isolated from a mammalian source with respect to the activity of the different folate polyglutamate derivatives, the reversibility of the reaction, and the effect of monovalent cations on the reaction. The iron-sulfur protein, ferredoxin, will be modified by chemical means in order to determine how the polypeptide portion of the molecule affects the redox properties of the iron-sulfur center, and the resulting biological properties of the substance. The enzymic factors affecting removal of the formylmethionyl moieties from the apoprotein will be determined. We will attempt to determine the structural differences that exist between the f-tRNA Met species that are formed by Streptococcus faecalis R when it is grown in the absence of folate compared to the structure formed when it is grown in the presence of added folate, and to explain why the species formed by the organism in the absence of folate permits initiation of protein synthesis to occur even when the methionyl-derivative is not formylated. We will attempt to demonstrate the biosynthesis of ferredoxin in the polysomal system derived from C. pasteurianum and to determine why the messenger-RNA derived from this preparation can stimulate protein synthesis by isolated clostridial ribosomes while messenger-RNA preparations from other sources are inactive in this system. BIBLIOGRAPHIC REFERENCES: Delk, A.S. and Rabinowitz, J. C. Biosynthesis of Ribosylthymine in the Transfer RNA of Streptococcus Faecalis: A Folate-Dependent Methylation Not Involving S-Adenosylmethionine. Proc. Nat. Acad. Sci. USA 72, 528-530 (1975). Packer, E.L. Sternlicht, H., Lode, E.T. and Rabinowitz, J.C. The Use of C13 Nuclear Magnetic Resonance of Aromatic Amino Acid Residues to Determine the Midpoint Oxidation-Reduction Potential of Each Iron-Sulfur Cluster of Clostridium acidi-urici and Clostridium pasteurianum Ferredoxins. J. Biol. Chem. 250, 2062-2071 (1975).